Liquid plant oil based polyol are polyols derived from vegetable oils like palm oil, soybean oil, coconut oil, sunflower oil, olive oil and canola oil. It is well-known in the art as numerous prior art has disclosed different approaches in producing polyols from plant oil. Most of the reported prior art revolves on methods that involves catalytic ring opening of the epoxy group of epoxidized oil to yield hydroxyl functionality.
The other more established method was hydroformylation that involves reacting plant oil derivatives such as fatty acid methyl ester (FAME) with synthetic gas in the presence of rhodium based catalyst.
It has been reported in Lligadas et al., Journal of Polymer Science Part A: Polymer Chemistry, (2006) that oligomeric polyols can be made from epoxidized methyl esters of plant oil's fatty acids. Epoxidized methyl oleate was oligomerized at room temperature for 1 hour in the presence of fluoroantimonic acid (HSbF6). Subsequently, the ester groups of the oligomers were partially reduced with lithium aluminium hydride (LiAlH4) to give primary alcohols. The oligomerization process yielded mostly trimer, tetramer and pentamer of methyl oleate with molecular weight ranges (Mn) from 930 to 1230 and hydroxyl value (OHV) ranges from 100 to 300 mg KOH/g sample.
Del Rio et al., in Journal of Polymer Science Part A: Polymer Chemistry (2010) also reported a process to produce plant oil based polyol from epoxidized methyl oleate. In this case, the epoxidized methyl oleate was oligomerized with various ionic-coordinative initiators such as tetraisobutylaluminoxane (TIBAO), TIBAO/iBu3Al and Vandenberg Catalyst [(C2H5)3Al/H2O]. All the reactions were conducted under dry argon using standard Schlenck techniques. The initial reaction temperature was 0° C., and then it was raised and maintained at 25° C. for 72 hours. The resulting white rubber-like polymers have molecular weight ranges (Mn) from 6000 Da to 8000 Da with predominantly linear polyether polyols.
PCT Publication No. WO 2004/096744 A2 has disclosed another method of making polyol from methyl ester which is known as hydroformylation. In this method, methyl linoleate was reacted with synthesis gas (1:1 mixture of hydrogen and carbon monoxide gases) in the presence of a rhodium based catalyst. The reaction was conducted at 400 psig pressure and 90° C. for 23 hours. The resulting aldehyde functional group of the hydroformylated methyl linoleate was then reduced with hydrogen gas to yield an alcohol group. The next step in the process involved the transesterification of the ester group of the hydroxyl functionalized methyl linoleate with polyether polyol to yield oligomerized methyl linoleate. The polyols produced from this method have hydroxyl value ranges from 25 to 80 mg KOH/g sample. However, there was no mention of the the molecular weight of the polyol.
Alternatively, renewable polyols can also be derived directly from the plant oil itself. U.S. patent application Ser. No. 60/786,594 has disclosed a process to make polyol from palm oil through a two steps process namely epoxidation and alcoholysis. The epoxidation was carried out at 70° C. for 9 hours with peroxy acids, preferably peracetic acid, which is prepared from hydrogen peroxide and the corresponding acid either in separate step or in situ to yield epoxidized palm oil. Then, the epoxidized palm oil was subjected to alcoholysis reaction, which was carried out at 70° C. for 1 hour with methanol or water as the ring-opener in the presence of fluoroboric acid as the catalyst. Further reaction between the hydroxyl groups formed during the alcoholysis reaction with unreacted epoxy groups yields oligomeric polyols, which mostly comprise of dimers and trimers of triglycerides. The oligomers content of the polyol was about 55% and the hydroxyl value of the polyol was about 55 mg KOH/g sample. However, the molecular weight of the polyol was not disclosed.
Similarly, U.S. Publication No. 20080293913 also disclosed a process to make polyol from a mixture palm kernel olein and soy bean oil through a two steps process namely epoxidation and alcoholysis. The epoxidation was conducted at 50° C. for 3 hours with peroxy acids, preferably performic acid, which was prepared from hydrogen peroxide and formic acid in a separate step to yield epoxidised plant oil. The epoxidized plant oil was then subjected to alcoholysis reaction with ethylene glycol (ring opener) at 60° C. for 1 hour and the reaction was catalysed by boron trifluoride etherate. The polyols produced from this method have hydroxyl value ranges from 70 to 130 mg KOH/g sample. The molecular weight of the polyol was not disclosed.
Liu et al., in Journal of the American Oil Chemists Society (2009) disclosed the use of boron trifluoride as the catalyst for ring opening of epoxidized plant oil. In this method, epoxidized soya bean oil was dissolved in methylene chloride and cooled to 0° C. Then, boron trifluoride etherate was added drop-wise and the reaction mixture was stirred at 0° C. for 3 hours. The products from this method were cross-linked polymers that were insoluble in most solvent. The same reaction could be conducted using liquid carbon dioxide instead of methylene chloride. The cross-linked polymers were subjected to soxhlet extraction and the soluble fractions of the cross-linked polymer ranges from 1% to 27% depending on reaction condition. The molecular weight of the soluble fractions ranges from 1600 Da to 3800 Da.
PCT Publication No. WO 2010/098651 A1 disclosed a method for epoxidation of plant oil, particularly to epoxidized palm oil and palm kernel oil. The chemo-enzymatic method of epoxidation of palm oil and palm kernel oil were performed with the presence of lipase as biocatalyst. The method of epoxidation of plant oil as disclosed comprises:                a) dissolving a mixture of oil in a non-polar solvent        b) adding enzymes (lipase) to the mixture        c) adding hydrogen peroxide gradually at a time interval        d) stirring the mixture        e) filtering the mixture for removal of enzyme        f) washing the mixture with a polar solvent        g) removing the solvent by evaporation        
Despite the fact that the reported prior art in preparing plant oil based polyol are diverse, it is evident that the synthesis of polyols from plant oil has several drawbacks. One of the drawback is the use of highly sensitive catalysts such tetraisobutylaluminoxane (TIBAO), TIBAO/iBu3Al and Vandenberg Catalyst [(C2H5)3Al/H2O], which need to be used under argon atmosphere. In addition, the use of the highly corrosive fluoroantimonic acid (HSbF6) is also another major problem. The use of these catalysts required specialized equipment for handling which increases the cost of production. On a separate issues related hydroformylation process, is the use of high pressure in the process of making plant oil based polyols. Again, this will required specialized equipment for the high pressure reaction condition which increases the cost of production.
Another drawback of the literature is the use of reaction temperature in the range of 60° C. to 70° C. for the epoxy ring opening reaction. The reaction will be more economical if it could be conducted at room temperature.
Furthermore, another drawback of the literature is the need to use ring opener such as water, methanol and ethylene glycol in the epoxy ring opening reaction in order to produce liquid polyol from epoxidsed plant oil. In the absence of these ring openers, the product of the reaction will be cross-linked polymer, which is not suitable for polyurethane application. The use of ring opener causes the yield of oligomers in the product to be less than 60%, which is not very economical for commercial production. In addition, the use of ring opener also increases the cost of production.
Present invention aims to achieve several objectives based on the embodiments of the specification which includes: i. to produce liquid plant oil based polyols without using highly sensitive catalysts to avoid the need for any specialized equipment for the process ii. to produce the liquid plant oil based polyols at atmospheric pressure and room temperature in order to keep the production cost at minimal iii. to produce liquid plant oil based polyols by ring opening of epoxidized plant oils where the polymer content of polyol is higher than 65% iv. to produce polyurea and polyurethane by using the produced liquid plant oil based polyol as the starting material.